FAQs, USB Specification

SuperSpeed USB 3.0 Specification: The Ultimate Guide to SuperSpeed USB 3.0

SuperSpeed USB 3.0 Specification The Ultimate Guide to SuperSpeed USB 3.0

USB 3.0, also known as SuperSpeed USB 3.0, is the biggest update to the USB specification yet. It promises higher performance with better power management than ever before. It was first introduced back in the Fall of 2007 at the Intel Developers Forum, but has become very popular only recently in 2012.

Transfer rates can go up to 4.8 Gbits/s as compared to 480 Mbits/s for USB 2.0. What this means is that USB 3.0 is can actually be up to 10 times faster than USB 2.0! This is made possible through its SuperSpeed Technology which allows multiple streams of data transfer.

In reality, even the fastest USB 2.0 devices are only able to reach about half of their theoretical bandwidth cap, topping out at close to 250 Mbits/s. The very first USB 3.0 devices to hit the market therefore only ran at about 2 Gbits/s, far below the 4.8 Gbits maximum, and yet still over 8 times faster than any USB 2.0 device currently available. Second generation USB 3.0 devices have been able to even rival SATA-II performance with calculated transfer speed close to 3 Gbits/s.

• Why make USB 3.0 so fast?

Video is one of the primary reasons necessary for the higher speed on the USB 3.0 specification. High Definition Video uses massive amounts of storage, and transferring video through USB 2.0 takes a whole lot of patience. This isn’t only in regards to video capture professionals, but for the average consumers with Digital Video Cameras as well. In short, handheld cameras are everywhere, and people are constantly filming and sharing video. Therefore, the need for a substantially quicker way to transfer HD video is absolutely necessary.

External storage devices, like external hard drives and USB drives, are also in need of a substantial speed boost, both for transporting and backing up data. eSATA and FireWire 1394 are currently the fastest ways to transfer large files, but neither had broad enough universal appeal in the market to achieve what USB 3.0 has set out to do – replace eSATA and FireWire as the global industry standard external interface for high speed data transfer. The very first USB 3.0 devices on the market were USB drive, external hard drives and digital video cameras. More recently, USB 3.0 has been implemented on both laptops and desktops, in addition to HDTVs.

• How does USB 3.0 work?

USB 2.0 has 4 wires. Two are for data lines, one for power and one for ground. USB 3.0 uses an additional 5 wires, with two transmit lines, two receive lines and an additional ground wire, for a grand total of 9 wires. The extra wires constitute an additional bus that works in parallel with the High Speed USB 2.0 port.

This particular architecture allows the USB 2.0 port to be fully functional for USB 2.0 devices while supporting the SuperSpeed transfer mode for USB 3.0 devices. It achieves full backward and forward compatibility. As you’ll see with the SuperSpeed Standard A connector below, the additional 5 pins are recessed into the back of the USB 3.0 plug. And unlike USB 2.0, SuperSpeed USB 3.0 can both send and receive data simultaneously. This is known as dual simplex signaling.

Another important change implemented in this specification is that USB 3.0 is asynchronous. Rather than broadcasting packets of data to every USB device, the controller will send packets asynchronously point-to-point, directly to the right device by using information contained in the data packet’s header. This takes away the need for something called “polling”, which is the routine check devices a required to make to see if there is any data to receive.

• What other new features are there?

• Will USB 3.0 work with my USB 2.0 ports and devices?

Yes. USB 2.0 and the outdated USB 1.1 devices are fully mechanically and electrically compatible with USB 3.0 ports and connectors. However, they will not achieve the speed provided by the USB 3.0 specification or be able to take advantage of its many features. USB 3.0 devices are also fully compatible with USB 2.0 and USB 1.1 ports and connectors, but they won’t run at SuperSpeed. To gain the advantages of SuperSpeed, you must use USB 3.0 device with USB 3.0 cables in a USB port with a USB 3.0 controller.

• How long before USB 2.0 disappears?

Well some people still use USB 1.1, so probably not for a long while. With an installed base of over 10 billion USB 2.0 devices, it’s safe to say that the USB 2.0 specification standard isn’t disappearing overnight. At first, USB 3.0 devices are bound to cost more than USB 2.0 because they require new and more complex controllers, cables, and connectors, so USB 2.0 and USB 3.0 will intermingle for many years to come. As the USB 3.0 specification becomes more widespread however, the cost difference between the two will narrow. Performance oriented storage and video devices will quickly migrate to USB 3.0 while low bandwidth devices like keyboards and mice will probably stay with USB 2.0 longer.

Here’s one projection of the adoption rate. This forecast shows USB 2.0 continuing to grow through 2012. The skinny red sliver at the top is USB 3.0, but don’t be fooled – the skinny red sliver grows to 500 million devices in 2012!

• Will I have to download drivers for USB 3.0?

Windows 7, OS X Mountain Lion, Linux 2.6.31 and later updates to these operating systems have support for USB 3.0. All of their predecessors will most likely have drivers or updates in the future to support it. It’s possible that you will have to install drivers for specific devices to enhance performance.

All About USB 3.0 Cables and Connectors

USB 3.0 cables have two additional shielded differential pairs (SDP) of wires for a total of 9 signal wires. 3.0 cables have to be shielded to prevent electromagnetic interference and maximize signal integrity. This means the cables are thicker, heavier, less flexible and more expensive than 2.0 cables.

There are several different USB 3.0 connectors, which are similar to the 2.0 connectors.

For More Information Visit:

• www.usb.org (USB Homepage)

• www.usb.org/developers/docs/usb_30_spec_052109.zip (Download – USB 3.0 Technical Specifications)

• en.wikipedia.org/wiki/Universal_Serial_Bus#USB_3.0 (Wikipedia – USB Article)

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